The options on the left determine how the entered keywords are interpreted if there are multiple word. The words have to be seperated by space. In case of the first option all words entered in the text field are taken taken as a single string, even if multiple words are enterd. E.g. entering Sony TV would only find occurances of exactly "Sony TV". It would not find Sony LCD TV. In case the second option "single words AND" is selected the search will turn up all the pages that contain all the words. In this case it will find any page that contains Sony and TV, even if they are separated or in reverse order. The last option of course will find all pages that contain any of the entered word.
The search term is not case sensitive. The search is done on a per coupon book page. This means a search for Sony TV will return a page that contains a coupon for a Sony Blu-Ray player and one for a Panasonic TV, even though there is no Sony TV coupon.